Fix #20 - Replace handler in multiple children

When toolbar has multiple children, we have to replace
handler in all of them. Example:

instance._toolbar = new A.Toolbar(
    {
        boundingBox: instance._userToolbar,
        children: [
            {
                // This handler will be changed to on click
                handler: function(event) {
                    instance._editEntry(contact);
                },
                icon: 'edit'
            },
            {
                /*
                 * This handler will be left alone, but
                 */ it should be changed too
                handler: function(event) {
                    instance._deleteEntry(contact);
                },
                icon: 'delete'
            }
        ]
    }
).render();